My current big HT system uses a pair of M60 like speakers up front, a heavily modified Merak (Axiom made) center channel (2 x 6.5" Axiom aluminum drivers and 3/4" Merak titanium tweeter) QS8 side surrounds and a pair of M2e back surrounds (SVS 20-39 and Velodyne CHT10 subs). I followed the general consensus that the M2s are excellent in the rear and swapped out a pair of Mission 77DS surround speakers for the M2e's. The 77ds are 90 db sensitive bipoles and are very musical.
I listen to SACD, DVD, CD and digital cable music. I think the set up with the Mission surround speakers in the back was better than the M2s at least in my room. For Home theater, I think the way to go is to use surround speakers in the side and back positions for 6.x or 7.x.
The bipole Missions integrated better with the subs than the M2e's do. Now, I think the M2s are excellent speakers. But, I prefer the M3Tis.
I never used my M3s in a HT system, I only used them in a 2 channel tube stereo system (2.1 with various subs). I did use a pair of M50s up front for a while. Nevertheless, I think the M3s would make an excellent front speaker pair for an HT system. If I were to build a 7.1 system around the M3Tis, I would get QS8S for the side and back surround positions. If you could find some Mission 77ds surrounds for cheap, I'd try them, they are also a very special speaker.
Here's one of the modified Meraks with the 3/4" tweeter and supertweeter.
Here's a picture of the second Merak I upgraded, this one with a big horn tweeter. In all immodesty, these are the best center channel speakers I've ever heard.